Schedule 31. Chaos Communication Congress

lecture: osmo-gmr: What's up with sat-phones ?

Piecing together the missing bits

At 28C3 we introduced the very first steps of the osmo-gmr projects. During this talk, we will present the various advances that have been made in this project on various aspects (voice codec, crypto algorithm, ...)

GMR-1 (GEO Mobile Radio) is a satellite phone protocol derived from GSM. The main operator using this protocol is Thuraya and is mainly active in the middle east and asia.

osmo-gmr is a project of the osmocom family whose goal is to implement the various levels of a GMR stacks, starting from SDR signal acquisition up to the actual voice layer.

At 28C3 we gave and introductory talk to the project which was pretty new at the time. On this talk, we will quickly summarize what was presented last time and then move on to the new stuff.

The two main obstacles to implement a practical monitoring software for GMR-1 were the secret crypto algorithm and the unknown voice codec. Both obstacles have now been lifted and we will present the details of how that happened. We will also look toward the next steps and other aspects of the system that we're planning to dig into.